for its expansion at \(\infty \) . For simplicity we assume that \(a(t)=1.\)  According to [1]}, the \(n\) -th Fourier coefficient of \(\mathrm {Sh}_t(f)\)  is given by
\(A_t(n)=\sum _{d|n}\varepsilon _{t,N}(d)d^{k-1}a\left(\frac{n^2}{d^2}t\right),\) 
